Cartridge



June 16, 1942. c, w Lm 2,285,775

CARTRIDGE Filed June 11, 1941 LEWIS C. WELDIN INVENTOR.

Patented June 16, 1942 ENE'EEE S'l'h'i'hfi PATENT FEEQE CARTRIDGE poration of Delaware Application June 11, 1941, Serial No. 397,531

Claims.

This invention relates to an improved center fired rifle cartridge and more especially to an improved center fired rifle cartridge which is exceptionally suitable and adaptable for firing at sub-zero temperatures.

The art has, in recent years, loaded the majority of military and sporting rifle cartridges with surface-modified progressive-burning double base smokeless powder especially to obtain higher bullet velocities and improved ballistics. Such powders are surface modified by some coating material such as, for example, a deterrent material as diethyldiphenylurea or with a deterrent explosive as dinitrotoluene or with mixture of the explosive or non-explosive materials. By the use of these heavy surface-modified double base powders, the burning of the powder grains is regulated so that in addition to increased bullet velocities reduced breech pressures are obtained. As is to be expected, the greater the surface modification of the powders, the more difficult they are to ignite, but the use of stron er primers has largely overcome this difiiculty.

Most rifles both military and sporting have increased the bullet velocity to such an extent that maximum limits have been placed on the breech pressures for safety reasons. The art, due to these limits has experienced difliculty in providing the high velocity ammunition required by military and sporting arms. The only solution to this ballistic problem has been in further modifying the grain surfaces of the various formulations of double base smokeless powder, but such modification has not solved the problem since higher strength primer must be used to obtain ignition and such primer, when the powder is fired at subzero temperatures, shatters the grains and causes great increases in breech pressures.

The increase in velocity has been applied to machine guns and in this type weapon the high breech pressures are exceptionally dangerous since there are so many fast moving parts. Likewise, a large percentage of the machine guns are now used in aircraft and operate at very low temperatures which emphasize the difficulties.

This invention has as an object the production of a rifle or machine-gun cartridge which will give high. bullet velocities with breech pressures within the allowable limits. A further object of this invention is to provide an improved means of igniting the heavily deterred double base propellent powder charge necessary in such cartridges. A further object of this invention is to provide a means of igniting a double base propellent charge an ignition primer centrally located within the base of the rifle cartridge which is of a reduced strength in comparison to the normal rifle primer and the ignition system, in addition to the detonating primer, has in conjunction therewith an ignition charge which is confined and attached within close proximity to the primer. The ignition charge is desirably contained within a silk bag which rests upon or is attached closely adjacent the primer. The ignition system of this invention provides a means of producing military and sporting cartridges that have greatly improved ballistics. Thus, by the novel ignition means consisting of a reduced strength primer and an ignition charge integrally contained and positively positioned adjacent thereto, the bullet velocity of rifles and machine guns may be maintained constant while the breech pressure is greatly reduced or the breech pressure may be maintained at a fixed value and the bullet velocity increased. It will be at once apparent to those skilled in the art that any means of accomplishing the above ballistic improvements constitutes a material improvement in the production of military or sporting rifle cartridges.

The invention includes the preparation of military or sporting rifle cartridges, of the center fire type, which have primers comparable in strength to those required for use with a black powder loaded casing instead of the normal detonating primer and the rifle cartridge casing includes an integral charge inserted within and attached or positively positioned adjacent the primer in the base of the center fired cartridge. The shell has a weak detonating primer in its base and the integral charge may comprise a black powder ignition charge contained within a silk bag or similar means and may be firmly positioned within the body of the cartridge and in contact with or closely adjacent to the weak detonating primer. This ignition primer is directed against the inteat sub-zero temperatures Without shattering the gral charge and this charge ignites therefrom and This invention may be applied to the various military and sporting center fire cartridges such as are used, for example, in the .30-06 Spring field, .303 British .50 caliber rifle, comparable machine gun or the large machine guns such as the mm. anti-tank or anti-aircraft weapons with a resulting decrease in breech pressure. The invention is most applicable, to the military rifle or to machine guns used in aircraft, since they are most often operated in sub-zero temperatures.

Having now indicated the broad scope of my invention, there follows a more detailed description of the preferred embodiment thereof with reference to the single figure. The figure represents a cross-sectional view of a rifle or machinegun cartridge which includes ignition means in accordance with this invention.

The figure represents a cross section of a loaded cartridge having a cartridge case I containing a double base propellent charge of surface-modified powder 2 and a projectile 4. The base of the cartridge case I is formed to receive a primer 5 which is a weak detonating primer and a black powder ignition charge 6 that is contained within a silk bag 8 positively positioned in contact or closely adjacent to the primer 5.

Operation of the above cartridge takes place as follows:

A firing pin, not'shown, strikes the weak detonating primer 5 which explodes and ignites the black powder charge 6 contained in bag 8 and this charge 6 burns with a long hot flame that does not give a shattering effect but that projects itself throughout the heavily deterred double base propellent powder charge 2 which is thereby efficiently ignited without shattering of the grains. The propellent charge 2 when ignited forces the projectile 4 through the barrel of the rifle. This propellent powder charge 2 is so regulated by the heavy surface modification and in relation to the black powder charge 6 that it and the bag 8 are completely burned by the time the projectile leaves the muzzle of the rifle barrel, thus developing the maximum velocity possible.

I have found that this novel means of igniting double base propellent charges gives greatly improved ballistics in military and sporting rifles and especially in aircraft machine guns. The novel ignition means in accordance with this invention presents no serious manufacturing difficulties as only the positioning of the bag 8 into the cartridge before insertion of the propellent charge is required in the steps of assembling cartridges. The bag may be positioned either by a small amount of adhesive or mechanically in the base of the cartridge.

To show the improvement in ballistics obtained by the use of the ignition primer of this invention, series of shots were made with normal cartridges and with the new cartridges of this invention. Thus, when a normal rifle cartridge was fired in a large caliber rifle with a 250.0 grain charge of heavily coated double base propellent powder and a standard rifle primer containing 2.0 grains of ignition charge, the mean breech pressure developed was about 47,500 pounds per square inch, and the mean bullet velocity developed was about 3,031 feet per second, while under the same conditions of testing, but using the ignition primer type cartridges in accordance with this invention, that is, a primer having only 0.5 grain of ignition composition and a silk bag containing 5.0 grains of FFFg black powder, the mean breech pressure developed was about 38,200 pounds per square inch, and the mean bullet velocity developed was about 2,903 feet per second.

The extraordinary decrease in mean breech pressure, amounting to over 8,000 pounds per square inch is very surprising and especially so when the bullet velocity of the two tests were only about one hundred feet apart. By the method of this invention, therefore, it is possible to decrease the breech pressure of rifle cartridges while maintaining the bullet velocity and this is a great improvement in the art. Further, as will be apparent, by the use of the ignition primers of this invention, it is possible to maintain the pressure level and raise the bullet velocity by using increased propellent powder charges or higher potential powders or more heavily deterred grams.

The ignition system of my invention is prepared by inserting a weak detonating primer such as a primer similar to those used in small arm center fire cartridges in which black powder propellent charges are used, for example, the Remington U. M. C. #1 or #1 rifle cartridge primers into the cartridge positioning a bag containing a black powder charge into the cartridge in contact or closely adjacent the primer and leading in the normal manner. The selection of a primer depends upon the ignition charge to be used which may be a black powder charge weighing up to about 10 grains depending upon the type of surface-modified propellent powder used in the rifle cartridge, although for most cartridges I have found that a Remington #1 or #1 primer and a 5 grain black powder charge is most desirable. The black powder which I find preferable to use is the sporting grade FFFg, but I do not limit myself to this specific ignition composition as it is obvious that other similar black powder may be used, and that I would use that granulation which by tests would give the best ballistics for the particular cartridge to be loaded. Further, I may substitute other flame-producing ignition compounds for black powder providing for each a suitable weak detonating primer.

The type of weak detonating primers which I have used in this invention normally contains an admixture comprising a detonating or ignition compound, an abrasive, and a binder and such primers are well known to and accepted by the art.

To demonstrate the improvement obtained by eliminating the excessive pressures developed upon firing cartridges at sub-zero temperatures, the following tests were made.

Large caliber rifle cartridges having normal primers containing 2.0 grains of priming mixture were loaded with a 250.0 grain charge of heavily coated double base powder and fired at room temperature and at sub-zero temperatures with the following results.

At room temperatures an average pressure of 43,300 pounds per square inch was recorded; while at -50.8 F., obtained by exposing the cartridges to solid carbon dioxide for 117 hours, an average pressure of 75,300 pounds per square inch with a maximum individual pressure of 83,600 pounds was recorded.

In the same gun with the same powder charges but using cartridges containing primers having 0.5 grain of priming mixture and 5.0 grains of FFFg black powder disposed in a silk bag and placed adjacent the primer gave the following results.

At room temperatures an average pressure of 35,600 pounds per square inch was recorded; while at 50.8 F., obtained by exposing the cartridges to solid carbon dioxide for 117 hours, an average pressure of 21,700 pounds per square inch with a maximum individual pressure of 22,600 pounds was recorded.

From the above results, it is obvious that the standard type cartridges with the known ignition system result in pressures which may be 100% higher than normal when they are fired at sub-zero temperatures, while by the method of ignition in accordance with this invention, the normal pressures have fallen off over 7,000 pounds at room temperatures and at sub-zero temperatures, the pressures instead of increasing have decreased by more than 13,000 pounds.

The protection gained by the ignition system of this invention is mostly marked in aerial combat since extremly low temperatures are encountered in the majority of incidents.

The means of positioning the ignition charge of this invention is preferably by using a silk bag of black powder, but it is to be understood that other means are contemplated such as, for example, by enclosing the charge within a bag or a pellicle of cellulose film such as nitrocellulose, regenerated cellulose, ethyl cellulose, cellulose acetate or the like or by binding the charge loosely together with an adhesive such as lacquer or the like. The ignition charge may be firmly positioned by an adhesive or it may be mechanically fastened into the cartridge and may be in some instances held in position by the propellent charge.

The ballistics obtained by using my improved rifie cartridges provides the art with means of greatly increasing the bullet velocity of the military cartridges without exceeding the maximum pressure limits which have been established. The desirability of increasing bullet velocity is well known to those in the art, and such improvement has been the object of much research. Further, the ignition primer of this invention is advantageous since it permits the use of more heavily deterred propellent powders without the danger of misfires, or ignition difficulties encountered with normally prirned cartridges and without danger of excessive pressures being developed by shattering of the grains when they are fired at very low temperatures. Also the advantage derived from actually reducing the breech pressures now produced in military and sporting rifles and maintaining a corresponding bullet velocity is a notable advance in the ballistic art.

It will be understood that the details and examples given hereinbefore are illustrative only, and in no way limiting on my invention as broadly described hereinbefore and in the appended claims.

This application is a continuation-in-part of my application, Serial No. 256,281, filed February 14, 1939.

What I claim and desire to protect by Letters Patent is:

1. A center fire rifle cartridge comprising a casing containing a primer, an ignition charge, a propellent charge and a bullet, the said primer being positioned in the base of the casing and having a strength not substantially stronger than a #1 Remington rifle primer, the ignition charge comprising a plurality of fine grain black powder contained within a combustible container and positioned as a unitary element within the casing and closely adjacent the primer, the propellent charge comprising a plurality of heavily deterred double base powder grains positioned against the said unitary ignition charge, and the said bullet positioned in the forward end of the said casing whereby the cartridge is characterized by an ability to maintain normal breech pressures when fired at sub-zero temperatures.

2. A center fire rifle cartridge comprising a casing containing a primer, an ignition charge, a propellent charge and a bullet, the said primer being positioned in the base of the casing and having a strength not substantially stronger than a #1 Remington rifle primer, the ignition charge comprising a plurality of fine grain black powder contained within a silk bag and positioned as a unitary element within the casing and closely adjacent the primer, the propellent charge comprising a plurality of heavily deterred double base powder grains positioned against the said unitary ignition charge, and the said bullet positioned in the forward end of the said casing whereby the cartridge is characterized by an ability to maintain normal breech pressures when fired at sub-zero temperatures.

3. A center fire rifie cartridge comprising a casing containing a primer, an ignition charge, a propellent charge and a bullet, the said primer being positioned in the base of the casing and having a strength not substantially stronger than a #l Remington rifle primer, the ignition charge comprising a plurality of ignition powder grains not substantially faster than black powder positioned within a pellicle and positively fastened as a unitary element within the casing and closely adjacent the primer, the propellent charge comprising a plurality of heavily deterred double base powder grains positioned against the said unitary ignition charge, and the said bullet positioned in the forward end of the said casing whereby the cartridge is characterized by an ability to maintain normal breech pressures when fired at sub-zero temperatures.

4. A center fire rifle cartridge comprising a casing containing a primer, an ignition charge, a propellent charge and a bullet, the said primer being positioned in the base of the casing and having a strength not substantially stronger than a #l Remington rifle primer, the ignition charge comprising a plurality of ignition powder grains not substantially faster than black powder positioned within a cellulose film and positively adhered as a unitary element within the casing and closely adjacent the primer, the propellent charge comprising a plurality of heavily deterred double base powder grains positioned against the said unitary ignition charge, and said bullet positioned in the forward end of the said casing, whereby the cartridge is characterized by an ability to maintain normal breech pressures when fired at sub-zero temperatures.

5. A center fire rifle cartridge comprising a casing containing a primer, an ignition charge, a propellent charge and a bullet, the said primer being positioned in the base of the casing and having a strength not substantially stronger than a #1 Remington rifle primer; the ignition charge comprising a plurality of ignition powder grains not substantially faster than black powder contained within a combustible container and positioned as a unitary element within the 10 casing and closely adjacent the primer, the propellent charge comprising a plurality of heavily deterred double base powder grains positioned against the said unitary ignition charge, and the said bullet positioned in the forward end of the said casing whereby the cartridge is characterized by an ability to maintain normal breech pressures when fired at sub-zero temperatures.

LEWIS C. WELDIN. 

